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Re: [PLUG] 8.04 to 8.10 Ubuntu-ings
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Before you obsess with the numbers in top, is your machine doing what
you expect it to do?
Once memory is allocated, the kernel will keep it around for use as
buffer/cache. Your 'free' memory, that stuff that hasn't been
allocated yet, is essentially wasted. Over time, you'll see the vast
majority of your memory is 'used'. Not all of that memory is actually
in use. For more accurate memory stats, you could check out the 'free'
command or maybe vmstat/pmap.
Actually, its a bit more complicated than that. Take for instance, a
shared library. If you're looking at the output of pmap, how do you
count the ram used for the shared libary? If its the only process
using it? If it isnt?
Take a close look at a few different processes via pmap. Notice any
/dev mappings? X11 has this wonderful tendency to map the video memory
into its address space (so that it can use it) making it look HUGE in
top. Also, those pixmaps in all those X11 apps? X11 maps those and
gets 'credit' for that memory usage too. I still think it's
unfortunate that device mappings show up as consumed memory. It causes
a bunch of x11/firefox complaints that aren't really well founded. The
real issue is that when you want to know exactly how memory is
allocated, it turns into a rats nest of details. Or, maybe, nobody has
written a decent memory profiler that has a 'detail' mode that really
lays it all out?
If you're concerned that something is leaking, you can always gather
stats via ps and free. If the vsize of a program is continually
sloping upward, you probably have a leak. If you're like me and have
pretty consistent usage patterns, your memory use will plateau after
the box has been up for a while. At that point all the shared libaries
and whatnot are loaded into memory. At that point, if you're swapping
hard, its time for ram. If you're not, then beyond fork bombs and
program errors causing leaks, you're probably fine.
This isn't a linux specific problem really. My mac and windows box are
the same in a lot of ways. I generally just use the systems in
whatever ways I plan on using them and dont worry too much about
memory usage unless its getting sluggish or having an actual problem.
Dont get me wrong, its valuable to understand where your ram is going,
but just keep in mind that top can be a bit misleading unless you
understand how the plumbing works.
On Sat, Dec 27, 2008 at 5:12 PM, jeff <jeffv@op.net> wrote:
> XUBUNTU IMPERSONATES WINDOWS
>
> I don't shut my desktops down. Lately I've been noticing humongous
> amounts of memory being used with almost no apps open. Even when I
> close all the GUI apps, it still indicates north of 70%. I initially
> figured it was Firefox leaking memory but I shut it down. Htop
> indicated it was xorg.
>
> I realize there are a certain amount of resources necessary to put
> things onscreen for a few days/weeks, but there used to be a time when I
> couldn't tell you the last time I rebooted. Now it looks like a week or
> more. I thought it might be dual monitor systems but it occurs with
> single monitor systems too. Is something not releasing RAM or does xorg
> think it will gain greater market share by behaving like Windows?
>
> All of the systems are Xubuntu 8.10 but I remember it happening on 8.04
> too. And this is supposed to be the `light' desktop... go figure.
>
>
>
> -=-=-
> ... The healthcare crisis will end when Congress has to choose an HMO
> * TagZilla 0.066 * http://tagzilla.mozdev.org
> ___________________________________________________________________________
> Philadelphia Linux Users Group -- http://www.phillylinux.org
> Announcements - http://lists.phillylinux.org/mailman/listinfo/plug-announce
> General Discussion -- http://lists.phillylinux.org/mailman/listinfo/plug
>
--
J.
___________________________________________________________________________
Philadelphia Linux Users Group -- http://www.phillylinux.org
Announcements - http://lists.phillylinux.org/mailman/listinfo/plug-announce
General Discussion -- http://lists.phillylinux.org/mailman/listinfo/plug
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